For many applications it is desirable to control both the transverse modes and longitudinal modes of the light generated by a semiconductor diode laser such that the output emission of the laser contains only a single longitudinal mode and a single transverse mode. An output emission containing only a single transverse mode is easy to focus, and has a substantially linear power output versus pump current relationship which is desirable for systems applications such as optical disk recording.
An output emission containing only a single longitudinal mode has a single frequency which could find applications in communications links using frequency multiplexing over fiber optic cables, holography, and in the production of visible light by harmonic generation.
In addition, an output emission containing only a single longitudinal mode and a single transverse mode from a laser having no end mirrors is desirable since the output can be coupled directly into a waveguide or other structure forming a part of an integrated optic system.